Continuity refers to the sense of cohesion that a work has. It relies on unity to achieve that cohesion. Rhythm (repetition) is a good way to create continuity. The more an idea or element is repeated the more continuity the work will have.
There are other ways that continuity can be achieved. For instance, in film the various aspects of the mise en scene sets/locations, costuming, properties, make-up, lighting, etcetera work together to from that coherence. When a western film is viewed one expects to see horses, mountains, praries, a wind torn town, spurs, guns, cowboy hats, ahps, rugged, dirty faces, etcetera. If a person dressed in a mini-skirt and flowered top were to come along it would create a clear anachronism.